1. Technical Field
This invention relates to a viscosity reducer and a method for manufacturing and using a viscosity reducer with active components based on vegetable extracts, to reduce the viscosity of heavy and extra-heavy crude oil, as well as reducing the consumption of diluents used in crude oil production systems.
2. State of the Art
Advances in exploration and production technologies in the petroleum industry are creating new major sources in areas that were previously off limits, for reasons of geography, politics and technology. Particularly, extra heavy crude oil has taken an increasingly important position in the oil market, due to the declination of traditional fields.
Some 80% of all heavy oils are extra heavy. These include oil sands, which are highly complicated as well as costly to develop. Although heavy oil is found in all parts of the world (e.g., Russia, USA, Middle East, Africa, Cuba, Mexico, China, Brazil, Madagascar, Europe and Indonesia), the largest accumulations are located in Venezuela (the Orinoco Belt) and Canada (the Province of Alberta). Combined, these two regions represent nearly 3,000 billion barrels of oil-in-place. They also account for 95% of global production of heavy oils (2.2 million barrels per day in 2008, two-thirds of which are in Canada and one-third in Venezuela). Less than 1% of these resources are in use or under active development today, and output should nearly quadruple, reaching at least 7 or 8 million barrels per day (Mb/d) by 2030. With such increases of heavy crude oil sources, now is a good time to exploit new avenues of research into the reduction of their viscosities.
Viscosity is the measure of resistance of a fluid to shear or tensile stress. In other words, the lower the viscosity of a fluid, the easier it is to move it. For example, low viscosity oil is much easier to move through a pipeline. Another way to comprehend the viscosity concept is to think of it as the internal resistance within a liquid to movement, akin to a fluid friction. Nearly all liquids have some resistance to movement and the branch of science studying this phenomenon is called rheology.
Crude oil or petroleum is a naturally occurring, toxic, flammable liquid consisting of a complex mixture of hydrocarbons of various molecular weights, and other organic compounds, that are found in geologic formations beneath the Earth's surface. The generally accepted theory of crude oil and natural gas formation is that over geological time periods, ancient biomass (kerogen) is heated and pressurized underground, finally converting to various grades and degrees of usable hydrocarbons.
Viscosity in crude oils is a direct function of the overall constituent hydrocarbons and can range from 200 centipoise (cP) for light crude oil to over 500,000 cP for bitumen. This large variability results in continuous development efforts by major oil and gas firms in enhanced oil recovery methods. A persistent problem in the thermal recovery of bitumen or very heavy oil is the very low mobility at the reservoir conditions. Despite improvements on thermal recovery methods such as Steam Assisted Gravity Drainage (SAGD) and Toe to Heel Air Injection (THAI), transportation of bituminous crude is highly problematic.
In order for these crude oils to be transported via pipeline from the source, typically the crude oils are blended with different types of diluents, such as kerosene, diesel, aromatic solvents, light oil, naphtha, and gasoline. This process has its disadvantages. Generally, up to 25% to 65% of diluent must be added to the blend for sufficiently reducing the viscosity, which uses up a great quantity of a valuable commercial product. Also, the added diluent must be processed again through the refinery along with the heavy crude oil, and usually some volume must be returned to upstream facilities to be used over and over.
Any viscosity reduction mechanism that does not need C+4 paraffinic hydrocarbons or light oil as diluents is in very high demand. Considering the ultra-rapid expansion of the Canadian Oil Sands and the potential expansion of Venezuelan Orinoco Belt hydrocarbons, this will only improve the importance of novel crude oil transportation technologies for energy industry. Today, the viscosity reduction effect of existing products in the market cannot fully meet the requirements of heavy, extra-heavy and bituminous oil exploitation.
So it is highly significant to carry out research on viscosity reduction mechanisms and develop viscosity reducers that meet the requirement of thick oil exploitation, extraction and transportation.
The addition of two oxygenates; methyl-tert-butyl-ether (MTBE) and tert-amyl-metyhl-ether (TAME) to reduce viscosity in heavy oils has been studied. Both MTBE and TAME are used as gasoline additives. It may be possible to add MTBE and TAME earlier in the production process in order to make use of their viscosity reducing and asphaltene precipitation prevention effects is now being studied. However, this does not solve the diluents transportation problem as both of these oxygenate products are produced at in the Gulf region and would require specialized pipelines for transport as well as reducing the oxidative resilience of crude oil.
There have also been a few attempts at using polymer-modified-bitumen (PMB) as a core technology platform for eliminating viscosity problem of the bitumen. However, results have been less than satisfying as polymers employed in the process interfere with most refinery chemical processes.
Accordingly, what is needed is a method of reducing viscosity in extra heavy crude oil (EHCO) production which yields savings by minimizing the consumption of diluent and increasing the oil production rate of heavy oil per day.